1. Field of the Invention
This invention relates generally to an intraocular lens and more specifically to an intraocular lens configured to reduce glare, improve adhesion to the eye, and/or mitigate unwanted cell migration such as posterior capsule opacification (PCO).
2. Description of the Related Art
The implantation of intraocular lenses represents one of the safest surgical procedures currently conducted and enjoys an extremely high success rate. One common use of intraocular lenses is for the replacement of natural lenses that have become clouded due to the formation of cataracts. Intraocular lenses have also found other uses, for example in the form of anterior chamber lenses that are implanted just behind the cornea in order to restore vision to patients that are extremely myopic or hyperopic.
One set of problems that are frequently encountered in the use of intraocular lenses is that of glare and posterior capsule opacification (PCO). Glare problems can occur due to edge effects from the implanted optic, which is typically much smaller than the natural lens being replaced. For example peripheral light entering the eye can be redirected by the edges of the optic, or even haptic portions connected to the optic, back toward the central portion of the field of view to create annoying and even dangerous glare images that are superimposed with the normal image formed by the center of the optic.
PCO typically occurs as a result of cells (epithelial cells) that migrate from the equatorial regions of the capsular bag into the optic portion of the intraocular lens. When this occurs, the result can be a loss of vision that is similar to that caused by the cataractous material that precipitated the surgery in the first place.
Another problem that may occur when an intraocular lens is implanted into an eye is that of poor adhesion of the intraocular lens to the eye, for example, poor adhesion to the capsule walls of a capsular bag into which the intraocular lens is placed. Good adhesion between the intraocular lens and the capsular bag can, for example, help maintain centration of the lens about the optical axis. In addition, good adhesion about the periphery of an optic may, at least in part, be important for reducing migration of epithelial cells toward the center of the optic. Adhesion can be particularly important in accommodating intraocular lenses, since these types of lenses typically require that force from the ciliary muscles and the capsular bag be effectively transferred to the intraocular lens so that the lens can translate or deform when changing between accommodative and disaccommodative states.
Various methods and device designs have been used to handle the duo of maladies common to intraocular lens implants. Examples include those disclosed in U.S. Pat. Nos. 6,162,249; 6,468,306; and 6,884,262, and U.S. Patent Application No. 2005/033422, all of which are herein incorporated by reference.
In some cases a solution for one of these two problems may actually exacerbate the other. For example, sharp corner edges about the periphery have been found to generally reduce the problem of PCO; however, such discontinuities may also have the unwanted effect of increasing glare due to the scatter of entering the intraocular lens from the peripheral field of view.
Further improvements and design options are needed for reducing the problems of both glare and PCO in patients receiving intraocular lens implants, as well as increase the adhesion of intraocular lens implants to the capsular bag.